Method and apparatus for obtaining cardiovascular information by measuring between two extremities

A method for obtaining information on the cardiovascular system non-invasively, continuously and beat by beat, comprising:

• a) injecting a current and measuring potential differences between two limbs, using a total of four electrodes which are, for each limb, a pair of electrodes including one injector electrode and one measuring electrode close to each other and located on a distal segment thereof;
• b) obtaining an electrocardiogram from the measuring;
• c) obtaining an impedance plethysmogram from the measuring;
• d) identifying specific predefined elements in the electrocardiogram and the impedance plethysmogram;
• e) measuring time intervals between the specific predetermined elements;
• and
• f) estimating cardiovascular information from said time intervals.

An apparatus for obtaining information on the cardiovascular system non-invasively, continuously and beat by beat, and containing:

• a) two pairs of electrodes, one electrode of each pair being a measuring electrode and the other a current injection electrode, both electrodes being close together;
• b) a current injection system to provide an injected current;
• c) an electrocardiogram system for measuring potential differences in voltage;
• d) a system for separating from the voltages measured a component coming from the electrocardiogram from a component coming from the injected current;
• and
• e) a calculation system obtaining cardiovascular information from the combination of the information coming from the electrocardiogram and the information coming from the injected current.